class Solution {
public:
    
    vector<int> sortArray(vector<int>& nums) {
       srand(NULL);
       qsort(nums,0,nums.size()-1);
       return nums;
    }

    // 快排
void qsort(vector<int>& nums, int l, int r)
{
    if(l >= r) return;

    // 数组分三块
    int key = getRandom(nums, l, r);
    int i = l, left = l - 1, right = r + 1;
    while(i < right)
    {
        if(nums[i] < key) swap(nums[++left], nums[i++]);
        else if(nums[i] == key) i++;
        else swap(nums[--right], nums[i]);
    }

    // [l, left] [left + 1, right - 1] [right, r]
    qsort(nums, l, left);
    qsort(nums, right, r);
}

int getRandom(vector<int>& nums, int left, int right)
{
    int r = rand();
    return nums[r % (right - left + 1) + left];
}
};